Implantable prostheses are commonly used in medical applications. One of the more common prosthetic structures is a tubular prosthesis which may be used as a vascular graft to replace or repair damaged or diseased blood vessels.
One form of a conventional tubular prosthesis specifically used for vascular grafts includes a textile tubular structure formed by weaving, knitting, braiding or any non-woven textile technique processing synthetic fibers into a tubular configuration. It is also well known to form a nontextile prosthesis, especially a tubular graft, from polymers such as polytetrafluoroethylene (PTFE). Such a nontextile tubular graft may be formed by stretching and expanding PTFE into a structure referred to as expanded polytetrafluoroethylene (ePTFE). Tubes formed of ePTFE exhibit certain beneficial properties as compared with textile prostheses. The expanded PTFE tube has a unique structure defined by nodes interconnected by fibrils. The node and fibril structure defines micropores which facilitate a desired degree of tissue ingrowth while remaining substantially fluid-tight. Tubes of ePTFE may be formed to be exceptionally thin and yet exhibit the requisite strength necessary to serve in the repair or replacement of a body lumen. The thinness of the ePTFE tube facilitates ease of implantation and deployment with minimal adverse impact on the body.
It is also known to use vascular grafts in conjunction with support structures. Such support structures typically come in the form of stents, which are formed of metal or polymeric materials generally formed in a tubular structure and are used to hold a vein or artery open. Stents are well known in the art and may be self-expanding or radially expandable by balloon expansion. Examples of stent/graft configurations known in the art can be seen in U.S. Pat. Nos. 5,700,285; 5,749,880; and 5,123,917, each of which are herein incorporated by reference. It is advantageous to use stent/graft configurations because the stent provides and ensures the patency of the prosthesis, while the vascular graft provides biocompatible properties in a vessel more suitable for blood to flow there through.
Various techniques have been discussed in the prior art for securing the stent and a graft to one and the other. For example, mechanical securement techniques have included the use of sutures, anchoring barbs, textile cuffs, and the like. These techniques increase the overall profile of the prosthesis and/or create stress points that may tear or otherwise deform the prosthesis. Further, bonding techniques have included adhesive and thermal bonding. The bonding techniques often result in limited bond strengths, especially in the longitudinal direction of the device. Often stents have been configured to have significant longitudinally traversing extents, in part to aid in stent-graft securement, but such extents also limit the overall profile of the device as these extents often limit the overall contractibility of the prosthesis.
It is therefore desirable to provide an implantable prosthesis, preferably in the form of a tubular vascular prosthesis, which achieves many of the above-stated benefits, such as low profile and enhanced stent/graft securement, without the resultant disadvantages associated therewith.